We came at 4. I asked the ticket attendant what time the zoo closed and was told 6. I also asked if the safari is included in the ticket price, and she told me yes and that the last one is at 5:45.
The park itself deserves 5 stars. You can interact with the animals, and you see them all, unlike the Phoenix Zoo where you need binoculars to see the animals.
The uneducated staff, however, sadly knocked it down to 3 stars. If the ticket attendant had just had told me that the last safari, which you had to pay separately for once inside unlike she told me, closed at 5, and that the park actually starts to kick everyone out at 5:15, then we would have saved our money and just came the next day to actually be able to enjoy the entire park.